1. Field of the Invention
The presently described technology generally relates to electrical control panels. More specifically, the presently described technology relates to capacitive touch electrical control panels for appliances.
2. Description of the Related Art
Capacitive sensors have become increasingly common and accepted for use in human interfaces and for machine control. In the field of home appliances, it is now quite common to find capacitive touch controls operable through functioning user interfaces or control panels. Touch controls, touch switches or touch pads are often used to replace conventional mechanical or tactile switches. Unlike tactile or mechanical switches, touch pads contain no moving parts to break or wear out. Moreover, touch pads can be mounted or formed on a continuous substrate sheet, such as a touch panel, without the need for openings in the substrate. The use of touch pads in place of mechanical or tactile switches can therefore be advantageous, particularly in environments where contaminants are likely to be present. Touch panels are also easier to clean than typical mechanical switch panels because they can be made without openings in the substrate that would allow penetration of contaminants. As a result, touch panels can offer a unique “high end” type of control panel experience, allowing a user to activate a control panel switch by placing an item such as a stylus or a finger at an area or a key of the control panel.
Although touch pads solve many problems associated with mechanical switches, known touch pad designs can still give rise to problems. For example, many known touch pads can malfunction when contaminants such as water or other liquids are present on the substrate. The contaminant can act as a conductor for the electric fields created about the touch pads, causing unintended switch actuations. This can present problems in areas where such contaminants are commonly found, such as household kitchens. Touch pads can also be susceptible to unintended actuations due to electrical noise or other interferences affecting a touch pad or the leads extending from the touch switch to its associated control circuit. This problem can be aggravated in applications where the touch pad is a relatively large distance away from the control circuitry.
Tactile control panels, on the other hand, offer their own benefits to users. For example, a tactile responsive control panel can offer an assurance to a user that the tactile response (or button, key, etc.) has indeed been activated. Such a response can be made with a noise such as a clicking of a button or a spring, or by the sensation provided by the depression of the tactile key, for example. Further, because tactile keys provide a mechanical mechanism for activating a switch, the tactile key can be separated from the circuit board by a distance without losing accuracy, such as in the form of a reduced signal to noise ratio, which can be present in a capacitive touch panel.
In certain situations, it is therefore desirable for an appliance producer to be able to offer an appliance for sale with an option of either a tactile responsive control panel or a capacitive touch control panel. It would be desirable to minimize the amount of differences in circuitry to reduce costs in manufacturing of the appliance with the multiple options and/or configurations. Further, in certain situations it is necessary to provide a touch pad that requires different functionality in various operation modes.
As a result, there exists an ongoing challenge to provide a control panel that operates as a capacitive touch panel and is easily adaptable to be used as a tactile control. Moreover, there exists an ongoing challenge to provide a circuit board assembly that can be used with either a capacitive touch panel or a tactile panel. Further, there is an ongoing challenge to provide a control panel having touch pads capable of performing multiple functionalities in a variety of operation modes.